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Title: The site occupation and valence of Mn ions in the crystal lattice of Sr{sub 4}Al{sub 14}O{sub 25} and its deep red emission for high color-rendering white light-emitting diodes

Highlights: • Different valences of Mn ions in Sr{sub 4}Al{sub 14}O{sub 25} were identified using XANES and EPR. • Red luminescence was attributed to Mn{sup 4+} occupying the center of AlO{sub 6} octahedron. • The Mn{sup 3+} incorporated in the center of AlO{sub 4} tetrahedron was non-luminescent. • The bond-valence theory was used to analyze the effective valences of cations. • A white LED device with CRI up to Ra 93.23 was packaged by using the red phosphor. - Abstract: The synthesis and component of red phosphor, Sr{sub 4}Al{sub 14}O{sub 25}: Mn, were optimized for application in white light-emitting diodes. The microstructure and morphology were investigated by the X-ray diffraction and scanning electron microscopy. Different valences of Mn ions in Sr{sub 4}Al{sub 14}O{sub 25} were discriminated using the electron paramagnetic resonance and X-ray absorption near-edge structure spectroscopy techniques. The bond-valence theory was used to analyze the effective valences of Sr{sup 2+} and Al{sup 3+} in Sr{sub 4}Al{sub 14}O{sub 25}. As a result, the strong covalence of Al{sup 3+} in the AlO{sub 4} tetrahedron other than in the AlO{sub 6} octahedron is disclosed. The deep red emission is attributed to Mn{sup 4+} occupying the center of AlO{sub 6} octahedron. The mechanismmore » of energy transfer is mainly through dipole–dipole interaction, revealed by the analyses of critical distance and concentration quench. A high color rendering white LED prototype with color-rendering index up to Ra 93.23 packaged by using the red phosphor demonstrates its applicability.« less
Authors:
 [1] ; ;  [1] ;  [2] ; ; ;  [1] ;  [3] ;  [4] ; ;  [5]
  1. School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China)
  2. Department of Chemistry, Hazara University, Mansehra 21300 (Pakistan)
  3. Department of Chemistry, Huaibei Normal University, Huaibei 235000 (China)
  4. National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan, ROC (China)
  5. National Synchrotron Radiation Laboratory, University of Science and Technology, Hefei, Anhui 230026 (China)
Publication Date:
OSTI Identifier:
22420703
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Research Bulletin; Journal Volume: 60; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ABSORPTION SPECTROSCOPY; ALUMINATES; ALUMINIUM IONS; CONCENTRATION RATIO; COVALENCE; CRYSTAL LATTICES; ELECTRON SPIN RESONANCE; LIGHT EMITTING DIODES; LUMINESCENCE; MANGANESE IONS; MICROSTRUCTURE; MORPHOLOGY; PHOSPHORS; SCANNING ELECTRON MICROSCOPY; STRONTIUM COMPOUNDS; STRONTIUM IONS; X-RAY DIFFRACTION; X-RAY SPECTROSCOPY